For the purpose of protecting a display surface of a display panel of e.g. a liquid crystal display device and an organic electroluminescence display device, it has been known to bond a transparent plate equipped with an adhesive layer to the display panel. Hereinafter, an organic electroluminescence display device will be referred to simply as an organic EL display device. For example, the following Patent Document 1 discloses a transparent plate having an adhesive layer, having such properties that when it is bonded to a display panel, voids are less likely to remain at the interface between the display panel and the adhesive layer.